Development of tebuconazole 0.5% paste for controlling rubber tree brown root disease

Brown root disease caused by Phellinus noxius Corner is one of the major root diseases of rubber trees in China. Common production practices include digging isolation ditches and root irrigation with pesticides for prevention and control of the disease, but they consume manpower and resources, resulting in high costs. In order to develop economically efficient and environmentally friendly new technologies, this study screened various fungicides, fillers, thickeners, penetrants, and moisturizers and developed an ointment for controlling the brown root disease of rubber trees. Subsequently, a comprehensive evaluation based on appearance, adhesion, viscosity, pH, stability, film-forming ability, and solid content loss rate was conducted. The optimal formulation determined includes 0.5% (mass fraction, the rest is the same) tebuconazole, 20% nanometer diatomite, 2% sodium carboxymethyl cellulose, 6% Wudier penetrating agent, 5% Vaseline, 5% palm oil, and the remainder is water. The prepared ointment exhibited a milky white, viscous consistency, slight alkalinity, strong adhesion, and high viscosity, and met the criteria for both cold and hot storage. The film formed by the cream was thin yet resilient with a solid content loss rate of 13.95% and it displayed strong resistance to rainwater erosion. A tebuconazole 0.5% paste was applied to the stem base of rubber plants in potted cultivation and the tebuconazole content in the roots was detected using GC-MS/MS combined with QuEChERs method. The results showed that tebuconazole could be detected in the roots 24 hours after application and the concentration significantly increased to 5.49 mg/kg after 96 hours. This suggests that tebuconazole penetrates the stem bark and translocates downward to the roots. In conclusion, the development of paste formulation provides a new approach to the chemical control of rubber tree brown root disease.